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Sending humans to Mars actually feasible?

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#1 StarWars

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Posted 20 July 2013 - 07:32 PM



Sending humans to Mars actually feasible?


http://news.yahoo.co...-100000933.html

#2 Joad

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Posted 20 July 2013 - 07:47 PM

This article pulls a very interesting rhetorical stunt. After noting, first, that no money at all has been set aside to pursue a Mars mission, it then describes the as-yet-unsolved barriers to such a mission. It then makes a leap—an incredibly large leap—to a discussion of some private firms that claim that they can get someone to Mars in no time, firms that haven't solved any of the problems.

Just because a couple of astronauts say they want this doesn't make it "feasible."

#3 Mister T

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Posted 21 July 2013 - 06:03 AM

They use the term "feasible"
But they cant pay the fee... ;)

#4 Ira

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Posted 21 July 2013 - 06:16 AM

Lots of silly stuff in that. "Single planet species don't survive." - Really? How could he possibly know. The part I liked best was the 3D printer for food. Remember Tang, the drink of astronauts? That was worth the multi-billion dollar price tag of the Apollo missions alone!

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#5 llanitedave

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Posted 21 July 2013 - 10:10 AM

It's feasible in principle. But not at the moment.

And if we don't even have the money to build a heavy lift launcher that flies more than once every two years, I don't think we're on the right track to get there.

#6 David Knisely

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Posted 21 July 2013 - 12:59 PM

Lots of silly stuff in that. "Single planet species don't survive." - Really? How could he possibly know. The part I liked best was the 3D printer for food. Remember Tang, the drink of astronauts? That was worth the multi-billion dollar price tag of the Apollo missions alone!

/Ira


The "Tang created by or for the space program" is a myth. Tang was created in 1957 and mainly got a PR boost when it was used in John Glenn's Mercury spacecraft flight in 1962 as well as in the Gemini spacecraft missions. Clear skies to you.

#7 Ira

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Posted 21 July 2013 - 05:34 PM

Close enough for rocket science work.

/Ira

#8 HiggsBoson

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Posted 21 July 2013 - 06:42 PM

A manned mission to Mars presents three problems. Fix any two and you are good to go.

• 10x increase in Propulsion efficiency – If one could increase the efficiency of propulsion by a factor of 10 one could get the same Delta V, change in velocity, using 1/10 the mass of fuel.

• 10x reduction in mass of radiation shielding - The mass of the shielding for the ship and the habitat on the surface is one of the driving factors that create the need for better fuel efficiency.

• 10x reduction in mass of expendables – The need to carry food and other expendables for a 2-year trip is one of the large drivers for a Mars mission. Unfortunately water is one of the expendables. I am unaware of any way to reduce the mass or volume of water. This means that the reductions in size and mass of food would have to be dramatically greater than 10x.

While it would be fun to go, I am unable to articulate a compelling business case that would convince a nation that the science value of this mission would be worth the cost. The argument for a commercial company is even poorer. I watched the US decide to build and LHC-like device in Texas and then change its mind. Now Europe will be the center of particle physics for the next couple of decades. I find the case for a manned Mars mission much weaker than for the LHC which the US declined to build.

#9 llanitedave

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Posted 21 July 2013 - 07:03 PM

Depending on where the landing site is chosen, much of the required water can be found already available on Mars. A lot of other supplies, including infrastructure necessary to melt the ice, can be launched prior to manned missions and cached in place.

All of these non-manned preparatory missions can be transported using a high-efficiency propulsion system similar to VASIMR, which should bring about significant mass savings.


All that, of course, is going to be extremely expensive, and I'd like to see a Mars mission be truly international in scope, and I'd like to see Mars prospected significantly enough in advance so that we can be fairly confident we're making an investment and not just an expenditure.

#10 Rick Woods

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Posted 22 July 2013 - 12:48 AM

"Single planet species don't survive." - Really? How could he possibly know.


Ira, everyone knows this - it's axiomatic. Eventually something happens to the planet to decimate the biosphere; the evolution of the sun if nothing else. Everything up to the death of the sun can be dealt with to a degree by spreading civilization throughout the Solar System. The end of the sun could be survived by spreading out to other stars.

It's not a science fiction scenario; sooner or later, the Earth will be finished as an abode of life. If humanity survives to that time and hasn't spread to other planets, that'll be the end of it all.

How do I know? How could anyone doubt? All things come to he who waits, including oblivion.

(None of which means we'll ever do anything about it. :()

#11 deSitter

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Posted 22 July 2013 - 03:32 AM

It's a matter of energy. If there is sufficient dense energy, we can go anywhere in the solar system. This is the greatest hope I have for cold fusion. If cold fusion can be mastered, we're home free - the rest is just technique.

I happen to have a crazy faith in our naturalness in the order of things. We're not here just to be trapped spectators.

-drl

#12 Ira

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Posted 22 July 2013 - 07:25 PM

"Single planet species don't survive." - Really? How could he possibly know.


Ira, everyone knows this - it's axiomatic. Eventually something happens to the planet to decimate the biosphere; the evolution of the sun if nothing else. Everything up to the death of the sun can be dealt with to a degree by spreading civilization throughout the Solar System. The end of the sun could be survived by spreading out to other stars.

It's not a science fiction scenario; sooner or later, the Earth will be finished as an abode of life. If humanity survives to that time and hasn't spread to other planets, that'll be the end of it all.

How do I know? How could anyone doubt? All things come to he who waits, including oblivion.

(None of which means we'll ever do anything about it. :()


Well, if you want to look at the long run, we are all dead, along with the universe, no matter what. So what's the difference between 1 billion years and a trillion years? Nothing in principle. So, if you're looking to avoid extinction in the long run you are just S.O.L. You'd have better success praying to God than going to Mars (or anywhere else). You can run but you can't hide from cosmic extinction.

/Ira

#13 Rick Woods

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Posted 23 July 2013 - 02:23 AM

"Single planet species don't survive." - Really? How could he possibly know.


Ira, everyone knows this - it's axiomatic. Eventually something happens to the planet to decimate the biosphere; the evolution of the sun if nothing else. Everything up to the death of the sun can be dealt with to a degree by spreading civilization throughout the Solar System. The end of the sun could be survived by spreading out to other stars.

It's not a science fiction scenario; sooner or later, the Earth will be finished as an abode of life. If humanity survives to that time and hasn't spread to other planets, that'll be the end of it all.

How do I know? How could anyone doubt? All things come to he who waits, including oblivion.

(None of which means we'll ever do anything about it. :()


Well, if you want to look at the long run, we are all dead, along with the universe, no matter what. So what's the difference between 1 billion years and a trillion years?


999 billion years. Maybe it's just me, but that seems significant.

Nothing in principle. So, if you're looking to avoid extinction in the long run you are just S.O.L. You'd have better success praying to God than going to Mars (or anywhere else). You can run but you can't hide from cosmic extinction.

/Ira


Are you absolutely sure of that?

#14 Ira

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Posted 23 July 2013 - 05:37 AM

You actually mean spread out to other stars, not other planets. If the earth is toast so are all of the semi-habitable planets in our solar system. So, the guy should have said, "Single star species don't survive." But maybe they do. It may be just as cost effective to make the earth habitable for all time as undertaking inter-stellar travel en masse, which for all we know is impossible, at least on a scale that would support species survival.

In any case, I'm willing to kick this problem down the road for another half-billion years while we continue to sort things out. It doesn't seem very urgent. I'd much rather spend the money on preparing to protect the earth from a renegade asteroid which is a more realistic and proximate problem, especially as far as species extinction goes.

/Ira

#15 Ira

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Posted 23 July 2013 - 05:50 AM

BTW, I believe I read somewhere that according to population genetics, the minimum starting size of a population required to insure its survival is around 130 persons, half male, half female. So, you're going to need alot more than a cosmic Adam and Eve if you want to keep humans hanging around for all time. Now getting that size population off the earth and surviving is in the realm of science fiction today. I'm not saying sending people into the cosmic vastness is pointless, it's just that the species survival argument for it is preposterous.

/Ira

#16 llanitedave

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Posted 23 July 2013 - 11:47 AM

BTW, I believe I read somewhere that according to population genetics, the minimum starting size of a population required to insure its survival is around 130 persons, half male, half female. So, you're going to need alot more than a cosmic Adam and Eve if you want to keep humans hanging around for all time. Now getting that size population off the earth and surviving is in the realm of science fiction today. I'm not saying sending people into the cosmic vastness is pointless, it's just that the species survival argument for it is preposterous.

/Ira


I've read that too, but I don't buy it. There are plenty of isolated species that seem to have gotten their start with as few as a single pair -- island species such as those on the Galapagos come to mind. The key, I think, is in how quickly the initial population increases from its starting point. In a large enough population, genetic deficiencies can be overcome and diversity increase, much more easily than in a small population.

I for one do think that the species survival argument is valid, although it won't be the human species itself that survives colonization of other star systems, but its descendents. We can't know what form those descendents will take, but given enough time, they are likely to look no more similar to us than we look similar to our own distant ancestral forms such as Pederpes. It's our lineage that we'd be wanting to preserve, not our current species form. That kind of extinction is inevitable no matter how many habitats we spread to, maybe even because of that diversification.

#17 Otto Piechowski

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Posted 23 July 2013 - 12:14 PM

"...cosmic Adam and Eve..."

Oooh! Oooh! Theology!

Otto

(Ira, I am not commenting about your comment or poking fun at you. I'm just, unfairly I might add, using your reference to poke fun at the folk here who get really nervous when issues of theology, philosophy, politics are raised).

#18 Jarad

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Posted 23 July 2013 - 12:18 PM

As a practical matter, if we don't figure out a way around the hard limit of C, I think that leaves us with 2 choices for interstellar travel:

1 - Large, multigenerational ships that are really miniature habitats in themselves, capable of supporting enough people to be a viable population. Of course, as Dave is fond of pointing out, once we do this there may not be much incentive to ever come back down to a planet, but just use asteroids/Oort cloud bodies to build more ships.

2 - Robotic ships that carry genetic samples from a large number of individuals to be used to artificially "jump start" a population when they reach a habitable planet. Genetic codes can be stored digitally. We are still a ways off from developing an artificial womb, but not that far off from being able to synthesize a full genome and insert it into an egg cell that has had its DNA removed. Eggs and DNA sequences don't weigh much. This bypasses the need for life support and greatly reduces the amount of mass you need to send. Also reduces the risk factor, since nobody is living on the ships.

Both will require significantly more advanced technology than we currently have to be feasible.

Jarad

#19 Jarad

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Posted 23 July 2013 - 12:21 PM

"...cosmic Adam and Eve..."

Oooh! Oooh! Theology!



Discussing the genetic issues of generating a population from a single original pair isn't theology. Arguing that all of humanity descended from a single pair that were divinely created would be. The reference to "Adam and Eve" was clearly used to indicate the former, not the latter.

Jarad

#20 Otto Piechowski

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Posted 23 July 2013 - 02:00 PM

True. That's why I said "unfairly".

But...."Adam and Eve" was used as a metaphor and analogy to make a serious statement and I believe some of us have been hammered here for making use of analogies from theology and philosophy and film and politics.

By the way, you Jarad, use analogy excellently when you teach me and others here things. I have, time and again, come away with a conceptual understanding of things I could not grasp because of your use of analogy.

Otto

PS....now I go to "C". Maybe you were able to do it there to!

#21 llanitedave

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Posted 23 July 2013 - 03:00 PM

As a practical matter, if we don't figure out a way around the hard limit of C, I think that leaves us with 2 choices for interstellar travel:

1 - Large, multigenerational ships that are really miniature habitats in themselves, capable of supporting enough people to be a viable population. Of course, as Dave is fond of pointing out, once we do this there may not be much incentive to ever come back down to a planet, but just use asteroids/Oort cloud bodies to build more ships.

2 - Robotic ships that carry genetic samples from a large number of individuals to be used to artificially "jump start" a population when they reach a habitable planet. Genetic codes can be stored digitally. We are still a ways off from developing an artificial womb, but not that far off from being able to synthesize a full genome and insert it into an egg cell that has had its DNA removed. Eggs and DNA sequences don't weigh much. This bypasses the need for life support and greatly reduces the amount of mass you need to send. Also reduces the risk factor, since nobody is living on the ships.

Both will require significantly more advanced technology than we currently have to be feasible.

Jarad


Dave is fond of that topic, isn't he? The problem with #2 is simply the fact that you can't just "jump start" a population by fertilizing eggs. If the DNA-store is of humans, they still have to be nurtured, socialized, entertained, educated, disciplined, and given site-specific training (without much in the way of prior experience to judge the quality of their training against) before they can be let off the ship. This strikes me as being pretty risky, and you still have a long period where you have to rely completely on automation to maintain an entire population of embryos through infants through teenagers.

I think achieving the speed of light might actually be easier.

The reason I keep pushing for plan #1 is because it requires the smallest leap in up-front technology, and the habitats can be improved incrementally with experience as we gradually evolve the skills and abilities to utilize first the main-belt asteroids, later Kuiper belt objects, and then gradually and cautiously moving into the Oort Cloud and beyond, eventually to other systems. It's not an all-or-nothing one-shot deal that way.

#22 ColoHank

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Posted 23 July 2013 - 03:50 PM

BTW, I believe I read somewhere that according to population genetics, the minimum starting size of a population required to insure its survival is around 130 persons, half male, half female. So, you're going to need alot more than a cosmic Adam and Eve if you want to keep humans hanging around for all time. Now getting that size population off the earth and surviving is in the realm of science fiction today. I'm not saying sending people into the cosmic vastness is pointless, it's just that the species survival argument for it is preposterous.



It's not like the human species can thrive in isolation, either. We're part of a web of life on Earth that includes a vast number of species interacting in ways we don't even understand. So, in addition to a seed population of humans, it also would be necessary to transport an incredibly diverse supporting cast of flora and fauna for colonization to work (in a nod to Otto, more cubits and pairs than Noah ever dreamed of).

#23 Otto Piechowski

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Posted 23 July 2013 - 04:07 PM

I had not considered what you, Hank, touched on, while I was silently following this thread; specifically, the need for a supporting environment of other flora and fauna to nurture a healthy human community over a period of years; and our lack of knowledge about what all is needed in terms of an ecological web of support.

Otto

#24 Jarad

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Posted 23 July 2013 - 04:19 PM

Yes, all true. We would need to bring a wide variety of plants, animals, bacteria, etc. with us.

Jarad

#25 Ira

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Posted 23 July 2013 - 05:18 PM

Pondering all of the problems I see the solution. It would be just as easy to put some thrusters on planet earth and let it be our big space ship. "Take us out of orbit, Mr. Sulu." And away we go... :step:

/Ira






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